Darwin’s Natural Selection Worksheet
Name ___________________________________
Read the following situations below and identify the 5 points of Darwin’s natural selection.
1)There are 2 types of worms: worms that eat at night (nocturnal) and worms that eat
during the day (diurnal). The birds eat during the day and seem to be eating ONLY
the diurnal worms. The nocturnal worms are in their burrows during this time. Each
spring when the worms reproduce, they have about 500 babies but only 100 of these
500 ever become old enough to reproduce.
Apply the Tenets of Evolution
Population has variations. _________________________________________________________________
Offspring inherit surviving parent’s traits. ___________________________________________________
More offspring are produced than survive.__________________________________________________
Some variations are favorable (& why).______________________________________________________
How will this population change over time? __________________________________________________
a. What worm has better “fitness”?________________________ Worse fitness?____________________
2) There are 3 types of polar bears: ones with thick coats, ones with thin coats and ones
with medium coats. It is fall, soon to be winter. The temperatures are dropping
rapidly and the bears must be kept warm, or they will freeze to death. Many of the
bears have had ~2 cubs each but due to the extreme temperatures, many mothers
only have one cub left.
Apply the Tenets of Evolution
Population has variations. _________________________________________________________________
Offspring inherit surviving parent’s traits. ___________________________________________________
More offspring are produced than survive.__________________________________________________
Some variations are favorable (& why).______________________________________________________
How will this population change over time? __________________________________________________
a. What bear has better “fitness”?________________________ Worse fitness?____________________
3) In ostriches, there are 2 types: ones that run fast and those that run slowly. The
fast birds can reach up to 40 miles an hour. Jackals love to eat ostrich, and they can
reach speeds of up to 35-40 miles per hour. A flock of ostrich will lay ~ 10 eggs
(each mother only lays 1), but many rodents break into the eggs and eat the fetus
before they hatch.
Apply the Tenets of Evolution
Population has variations. _________________________________________________________________
Offspring inherit surviving parent’s traits. ___________________________________________________
More offspring are produced than survive.__________________________________________________
Some variations are favorable (& why).______________________________________________________
How will this population change over time? __________________________________________________
a. What ostrich has better “fitness”?________________________ Worse fitness?____________________
4) Bob believes that giraffes have long necks because they have stretched their necks to
try and reach food that is high in trees. Since the parent had stretched its neck, it is longer
than it was supposed to be when it was born and longer than its parents. It passed the long
neck on to its offspring. Ryan believes that giraffes have long necks because the ones with
long necks were able to reach the food, and those with short necks could not and died. The
long necked giraffes reproduced, and soon all of the giraffes had long necks.
a. Who thinks like Lamarck? __________________________________________________
b. Who thinks like Darwin? ___________________________________________________
c. In each of these scenarios the population changes over time. Who is responsible for affecting the
change in the populations, the individuals or the surrounding environment?
5) Compare population 3 with population 1. If evolution is change in traits over time…
a. Did the population evolve?
b. Give the specific reason why you answered
this way.
c. Which trat is selected for?
d. Which trait is selected against?